The fungicidal treatments for vines currently in common practice find their origin in the appearance, in the 19th century, of two original fungal parasites from America:
powdery mildew (Uncinula necator) introduced into France in 1847 PA1 mildew (Plasmopara viticola) introduced into France in 1878 PA1 Bordeaux mixture for the mixture of copper sulphate with a milk of lime, PA1 Burgundy mixture for the mixture of copper sulphate with calcium carbonate. PA1 the direct process consisting of the introduction of a milk of lime into an aqueous copper sulphate solution, PA1 the reverse process, according to which an aqueous copper sulphate solution is introduced into a milk of lime. PA1 poor dispersion in water PA1 production of a sticky deposit in the spray tank, leading to plugg nozzles PA1 appearance of burns on the leaves on account of the acidity of the product. PA1 devillite: CaCu.sub.4 (SO.sub.4).sub.2 (OH).sub.6 !.3H.sub.2 O PA1 posnjakite: Cu.sub.4 (SO.sub.4)(OH).sub.6.H.sub.2 O PA1 brochantite: Cu.sub.4 (SO.sub.4)(OH).sub.6 PA1 antlerite: Cu.sub.3 (SO.sub.4)(OH).sub.4 PA1 gypsum: CaSO.sub.4.2H.sub.2 O PA1 bassanite: CaSO.sub.4.1/2H.sub.2 O. PA1 Bordeaux mixture as sole fungicide PA1 combination of this Bordeaux mixture with at least one synthetic fungicide in the following presentations: PA1 formulations of WP type (wettable powder) which are dispersible in water PA1 formulations of WG type (dispersible granule) of higher apparent particle size (from about 50 to 400 .mu.m) which are dispersible in water and release little or no dust at the time of use PA1 liquid formulations of SC type (suspension concentrate) which are also dispersible in water.
which have since become endemic parasites.
In order to control these parasites, use is still made of two products of inorganic origin (sulphur to combat oidium and copper to combat mildew), since their use in successive treatments does not induce any phenomenon of resistance, as is often the case with synthetic fungicides.
As regards copper, the sulphate form is seen to be the simplest to use on account of its solubility in water. However, since the acidity of this solution leads to burns on the vine leaves, it has proven necessary to incorporate a product of basic nature therein in order to decrease the acidity by neutralization. Lime and calcium carbonate have been used for this purpose, giving rise to what is known as:
Bordeaux mixture has become, little by little, the product most widely used in viticulture and its use as a fungicide has even extended to other cultures (vegetables and fruits) and to other parasites, in particular bacteriosis and scab.
The two most common processes for the industrial production of a Bordeaux mixture are:
However, irrespective of the process used and despite the technical improvements made, the fungicidal compositions formulated from current industrial Bordeaux mixtures often have drawbacks at the time of their use, in particular:
The use of a standard Bordeaux mixture in the formulation of a concentrated aqueous suspension (liquid formulation of the SC type) leads, on storage, to the gelation and setting and caking of the suspension to a solid. In the formulation of water-dispersible granules (formulation of WG type), the use of a standard Bordeaux mixture leads, on storage, to a reinforcement of the cohesion of the granules with, as an effect, poor redispersion of these granules during use. The use of a standard Bordeaux mixture in the formulation of a wettable powder (formulation of WP type) leads, on suspending this powder in water, to the formation of a sticky deposit.
X-ray analysis of a standard Bordeaux mixture reveals a polyphasic and variable composition of copper complexes, consisting of:
as well as a polyphasic and variable composition of calcium complexes, consisting of: